Hydrocarbon conversion



Dec- 3, 1942- E. H. McGREw HYDROCARBON CONVERSION INVENTOR EDWIN MC GREWTTORNEY Patented Dec. 8, 1942 UNITED STATES PATENT OFFICE HYDROCARBONCONVERSION Edwin n. McGrew, chicago, nl., assigner to-Umversal OilProducts Company, Chicago, lll., a

corporation of Delaware Application September 30, 1939, Serial No.297,223

8 Claims.

This invention relates to a process for producing principally aviationgasoline but when desired both motor and aviation gasoline, and morespeciically it is concerned with a novel combination of interdependentsteps wherein hydrocarbon oils of diierent characteristics and selectedirl-- any desired mixture thereof, thermal cracking treatment of` arelatively heavy hydrocarbon oil, such as topped or reduced crude, hightemperature catalytic cracking treatment of an oil intermediate to thetwo first mentioned oils, such as kerosene or gas-oil, polymerizationtreatment of the gases formed in the process, and low temperaturecatalytic cracking treatment of the gasolines formed in the process,including the polymer gasoline, in commingled state with lightintermediate conversion products from the thermal cracking and reformingtreatments.

The gasolines formed in the thermal cracking and reforming and hightemperature catalytic cracking treatments generally contain highpercentanges of olenic hydrocarbons and, of course, the polymer gasolineformed by the polymerization of oleilnic gases is predominantly olenic.These gasolines, naturally, due to their high oleiln content, have highoctane ratings, but their susceptibility to anti-knocking agents isrelatively poor. In additiorn, cracked gasolines containing a highpercentage 'of olens, after relatively short storage periodsandvfrequently upon use, have been shown to contain undesirable gumcompounds. The cracked gasolines employed as ordinary motor fuel, at thepresent time, are inhibited -with suitable antioxidants to retard theformation of gums, and this method, in so far as gasoline for motorvehicles is concerned, has

proven to be entirely satisfactory. l

The standards adopted for aviation gasoline, on the other hand, requirea gasoline containing a relatively small proportion of oleilns in order'to limit the possibilities of motor failure due to the presence orformation of gums in the gasoline. I have found that I can produce agaso-' line of low potential gum content, which meets the acid heatrequirements, and upon the addition of minor amounts of antiknocklngagents the octane requirements of aviation gasoline by subjecting anyone or al1 of gasolines formed in in the high temperature catalyticcracking treatment and the gas polymerization treatment to lowtemperature catalytic cracking treatment in the presence of intermediateconversion products formed in a thermal cracking treatment. The gasolineproduced in this manner has a relatively low olefin content and a goodsusceptibility to antiknocking agents.

The term thermal cracking treatment as used throughout the specificationand claims refers to the conversion of heavyhydrocarbons into,

lighter hydrocarbons by heat and pressure. and in all cases involves thescission of carbon to carbon bonds, although other reactions may also beinvolved. The term thermal reforming treatment, on the other hand,refers to the treatment of relatively light hydrocarbons to improvetheir octane rating and may involve the scisson of carbon to carbonbonds, the scission of carbon to hydrogen bonds, cyclization, and manyother reactions of lesser importance. The term polymerization treatmentrefers generally to the polymerization of oleiinic gasesinto normallyliquid polymers in the presence of suitable polymerizing catalysts, suchas phosphoric or sulphuric acids. The term high temperature catalyticcracking treatmei t refers to the treatment of hydrocarbon oils i i thepresence of catalytically active masses a temperatures ranging, forexample, from 800 to 1200 F., at pressures varying vfrom substantiallyatmospheric to 200 pounds or more per square inch, and at a. liquidhourly space velocity of from 2 to 10 volumes of hydrocarbon material per volume of catalyst to effect substantial conversion to gasolineboiling range hydrocarbons and ordinarily involves the scission ofcarbon to carbon bonds, although other reactions, such as cyclization,and the scission of carbon to hydrogen bonds may also take place. Theterm low temperature catalytic cracking treatment refers to thetreatment of hydrocarbons at relatively low temperatures ranging, forexample, from 500 to 900 at pressures ranging from substantiallyatmospheric to 200 pounds or more per square inch.' and at liquid hourlyspace velocities of from .5

alytic cracking is essentially one of transferring the thermal crackingand reforming treatments hydrogen from the heavier hydrocalbOnS t0 thelighter olefinic hydrocarbons to convert the latf ter into paraftlnichydrocarbons, although cracking, cyclization. and isomerization may alsobe involved. It is believed that in the low temperature catalyticcracking treatment saturated hydrocarbons and particularly thenaphthenic hydrocarbons of the intermediate conversion products act ashydrogen donors for the oleflnic hydrocarbons of the gasoline, while theolenic hydrocarbons become saturated to form parafflnic hydrocarbons andthe naphthenic hydrocarbons are converted to aromatic hydrocarbons.Various other reactions, such as, for example, dehydrogenation andcyclization of an aliphatic hydrocarbon to form an aromatic hydrocarbonwith the formation of two or three molecules of hydrogen which attach tothe unsaturated oleflnic hydrocarbons may also take place. However,since the invention is.` concerned primarily with a process andapparatusin which the various reactions may be conducted, further discussion withregard tothe chemical reactions which may possibly be involved isunnecessary,

for a full understanding of the invention which is to be described inmore detail later.

In one specific embodiment the invention comprises subjecting arelatively heavy hydrocarbon oil and a heavy reflux condensate topyrolytic conversion in athermal cracking system, concurrently therewithsubjecting a relatively light hydrocarbon oil to pyrolytic conversion ina thermal reforming system, commingling the conversion products fromsaid thermal reforming system and said thermal cracking system,separating a non-vaporous liquid residue from the vaporous conversionproducts of the mixture and i recovering the former, fractionatlng saidvaporous conversion products to form light and heavy reux condensatesand to separate fractionated vapors in the gasoline boiling range,concurrently subjecting a hydrocarbon oil boiling intermediate to thetwo first mentioned oils, to.- gether with intermediate conversionproducts formed in this and a subsequent step to conversion in a hightemperature catalytic cracking system, fractionating the conversionproducts from said high temperature catalytic cracking system toseparate liquid residue, intermediate conversion products, and gasolineboiling range vapors, recovering said liquid residue, subjecting theintermediate conversion products to further conversion in the samesystem, commingling said gasoline boiling range vapors with saidfractionated vapors from the iirst mentioned fractionation andstabilizing the mixture to remove light reflux condensate from the firstmentioned fractionation and subjecting the mixture to conversiontreatment in the low temperature catalytic cracking system,fractionating the conversion products from said low temperaturecatalytic cracking system to separate gasoline boiling rangehydrocarbons from the higher boiling components, supplying said higherboiling components to the conversion treatment in said high temperaturecatalytic cracking system, cooling and condensing said gasoline boilingrange hydrocarbons andl recovering the resulting distillate. and gas asproducts of the process. f

The accompanying drawing illustrates diagrammatically the flow of theinvention. Simplifled means have been adapted in illustrating thevarious conversion systems for convenience and for ease in demonstratingthe flexibility of the process. Y Referring now to the drawing, arelatively heavy hydrocarbon oil, such as, for example,

topped or reduced crude oil is introducedv through line l to thermalcracking system 2. Concurrently therewith, heavy reflux condensate;formed as hereinafter described, is likewise introduced to thermalcracking system 2. The hydrocarbon oil and heavy reflux condensateintroduced to thermal cracking system 2 are subjected to pyrolyticconversion therein in either the same or separate heating coils and theconversion products thereafter subjected to prolonged conversion, whendesired, in a communieating reaction chamber. Conversion temperaturesemployed in system 2 may vary depending upon the type of charging stocktreated and whether one or more heating coils are employed. However, ingeneral, conversion temperatures will fall within the approximate rangeof 800 to 1000 F. while employing superatmospheric pressures of from 100to 500 pounds or more per square inch. 'I'he conversion products fromcracking system 2 are directed through line 3 into vaporzing andseparating bzone 4, which is preferably maintained at a reduced pressurerelative to that employed in system 2, in orderl to obtain a sep--aration between the vaporous and liquid conversion products and toeiIect substantial further -vaporization of said liquid conversionproducts to form a non-vaporous liquid residue. The pressure employed inzone 4, depending upon the conditions employed in system 2, may range,for example, from 25 to 200 pounds or more per square inch.

In addition to the thermal cracking treatment of a heavy hydrocarbonoil, the invention also proposes to thermally reform a relatively lighthydrocarbon oil, such as gasoline, naphtha, or

' kerosene, or any mixture thereof, and to catalytically crack anintermediateoll, such as gasoil, at relatively high temperatures toproduce more valuable products than either of the two last mentionedcharging stocks. The use of either of these operations is optional andmay depend upon the amount of high octane substantially saturated motorfuel desired, which may vary for each speciilc case. In accordance withthe objects of the invention, however, since both thermal reforming andhigh temperature catalytic cracking yield a gasoline product rich inoleiinic hydrocarbons and since the objective inail cases is to treateach hydrocarbon oil under the optimum `conditions for the production ofmotor fuel, such operations may be conveniently employed in combinationwith a thermal cracking treatment and the gasolines produced in allcases subjected to low temperature catalytic cracking treatment toproduce a substantially saturated motor fuel.

Thermal reforming treatment, in the case here ample, gasoline, naphtha,or kerosene, or 4any i mixture thereof, through line 5 into thermalreforming system 6. Thermal reforming system i, in most instances, willcomprise a heating coil to which the hydrocarbons -are charged and willemploy conversion temperatures ranging, for example, from 900 to 1050 F.and superatmospheric pressures of the order of 500 to 1200 pounds ormore per square inch. The conversion products from system 6,`in the casehere illustrated, are directedthrough line 1, commingling in line 3 withthe conversion products from system 2 and the mixture thereafterintroduced to zone 4 where the vaporous components are separated fromthe liquid components in the manner previously described.

Liquid residue separated in zone 4 is removed therefrom by way of line8, cooled and recovered as a product of the process, or subjected to anydesired further treatment,rthe latter comprising, for example, coking orsolvent extraction. Vaporous conversion products, together with vaporsevolved Within zone 4, are removed therefrom by way of line 9 andintroduced to fractionating-zone I0, which is preferably maintained at asuperatmospheric pressure substantially the same as that employed inzone 4.

The vapors introduced to fractonating zone I A are subjected tofractionation therein to separate fractionated vapors boiling in therange of gasoline or, when desired, containing hydrocarbons boilingabove the range of gasoline from the higher boiling components and the.latter condensed in zone I0 as light and heavy reux condensate.` Heavyredux condensate formed in zone I0 is removed therefrom by way of lineII and introduced to thermal cracking system 2, either by comminglingthe same with the heavy hydrocarbon oil in line I when a single heatingcoil is employed, or by introducing the heavy redux condensate to'system2 by way of line I2 when separate heating coils are employed.Fractionated vapors separated in zone l0 are removed therefrom by way ofline I3, preferably cooled and introduced to stabilizing zone I4 fortreatment as hereinafter described either alone or in commingled statewith cooled vapors boiling substantially in the range of gasoline,formed as subsequently described, in a high temperature catalyticcracking system.

When the high temperature catalytic cracking system is employed, an oilboiling intermediate to the thermal cracking and thermal reformingstocks is introduced through line I5 to high temperature catalyticcracking system I6, either alone or in admixture withintermediate'conversion products formed in the system, or in asubsequent low temperature catalytic cracking system. The hightemperature catalytic cracking system I6 may comprise, for example, aheating coil wherein the intermediate hydrocarbon oil or the mixture isvaporized and raised to the desired conversion temperature, preferablyin the absence of pyrolytic cracking. In addition, system IO included areactor zone, and preferably a plurality of reactor zones containing asuitable crackingl catalyst with which the hydrocarbon vapors arecontacted preferably while maintain- Cil ing the temperature of thevapors substantially the same as that employed on the outlet of theheating coil. In addition, since relativelys short periods of operationare employed in the catalytic cracking because of the rapid depositionof carbon upon the surface and within the pores of the catalystparticles, provisions are made for reactivating the catalyst and forsegregating one or more of the reactors to accomplish reactivation whileconversion of the hydrocarbon vapors is being accomplished in the otheror others.

The preferred cracking catalysts for use in the present process consistin general of a precipitated alumina hydrogel and/or zirconia hydrogelcomposited with silica hydrogel, the gel composite being washed, dried,formed into particles, and calcined to produce a catalytic mass. It isnot intended, however, that the process should be limited to theseparticular catalysts, for other catalysts, such as. for example, thehydroslicates of alumina, acid treated clays, and-the like, may be usedwithin the broad scope of the invention.

In the following specification yand claims the terms silica, alumina,silica-zirconia,-and silicaalumina-zirconia masses are usedv in thebroad sense to designate the synthetic composites referred to above. Thepreferred catalysts may be prepared by precipitating silica from asolution as a hydrogel within or upon which the alumina and/or zirconiaare deposited also by precipitation as hydrogels. The silica hydrogelmay conveniently be prepared by acidifying an aqueous solution of sodiumsilicate by the addition of a required amount of hydrochloric acid.After precipitating. the silica gel is preferably washed untilsubstantially free from alkali metal salts. The washed silica hydrogelis then suspended in a solution of alumina and/or zirconia salts and analkaline precipitant, such as ammonium hydroxide, ammonium carbonate orammonium sulfide added to the solution to precipitate aluminum and/orzirconium hydrogels, The final precipitate, comprising essentiallyhydrated silica and hydrated alumina and/or zirconia, is washed tosubstantially completely remove water soluble materials and dried atabout 300 F. and pelleted or sized to produce particles of catalystafter which the catalyst particles are calcined at a temperature in theapproximate range of 1000 to 1500" F. Various other procedures, such as,for example, coprecipitation of the hydrated gels may be employed,'whendesired, to produce the preferred catalyst.

When using the preferred catalysts temperatures of the order of 800 to1200 F. may be employed with a pressure ranging, for example, fromsubstantially atmospheric' to 200 pounds or more per square inch andwith liquid hourly space velocities of from 2 to 10 volumes ofhydrocarbon material per volume of catalyst.

The conversion products from system I6 are removed therefrom by way ofline I'I and introduced to fractlonating zone I8, which is maintem I6,provisions may be made in zone I 8 for separating the same from thelighter hydrocarbons. This may be accomplished by separating thenon-vaporous liquid hydrocarbons from the vaporous hydrocarbons-in thelower portion of zone I8 and recovering the former by way of line Il.The lighter vaporous hydrocarbons are fractionated in zone Il toAseparate vapors boiling substantially in the range of gasoline or,

when desired, vapors, including hydrocarbons. boiling above the range ofgasoline from the higher boiling hydrocarbons, the latter beingcondensedl in the fractionating zone. Reflux condensate formed in zone.Il is removed therefrom by way of line and subjected to furtherconversion in system I6, as previously described, or supplied in part orall to thermal cracking system 2 by directing the same through line 2Iinto line II and commingling it therein with reiiux condensate from zoneI0. Vapors separated in zone I8 are removed therefrom by way of line 22and commingled in line I3 with fractionated vapors from zone I 0, aspreviously described.

Vapors from zones I8 and I0, preferably after cooling and condensationthereof, are subjected to stabilization in zone I4 by fractionation toremove substantially all of the normally gaseous hydrocarbons. Toaccomplish this, zone I4 is preferably maintained under asuperatmospheric pressure of from 50 to 200 pounds per square inch witha top temperature of from 100 to 200 F. The normally gaseoushydrocarbons and hydrogen separated in zone I4 are removed there'- fromby way of line 23 and introduced to deethanizing zone 24 which isoperated under a superatmospheric pressure ranging, for example, from400 to 800 pounds or more per square inch,

vwherein the Cz normally gaseous hydrocarbons.

methane, and hydrogen are separated by fractionation from the heaviernormally gaseous hydrocarbons. The light gas fraction, including .the C2hydrocarbons separated in zone 24, is removed therefrom by Way of line25 and recovered as a product of the process or subjected to any desiredfurther treatment.

The heavy normally gaseous hydrocarbons separated in zone 24, whichinclude the Ca and C4 hydrocarbons, are removed therefrom by way of line26 and introduced to polymerization system 21. Polymerization system 21may comprise, for example, a heating coil or heat exchanger used forheating the normally gaseous hydrocarbons to the desired polymerizingtemperature. In addition, it may include a reactor, and preferably aplurality of reactors containing polymerizing catalysts with which thenormally gaseous hydrocarbons are contacted. Furthermore, reactorsemployed in system 21 are preferably provided with a means forwithdrawing heat during the polymerization reaction.

Catalysts which may be employed for effecting polymerization in system21may comprise, for example, a phosphoric acid-containing catalyst or asulfuric acid catalyst. However, sulfuric acid is more selective to thepolymerization of the C4 hydrocarbons, and particularly lsobutene, andtherefore the phosphoric acid-containing catalyst is the preferredcatalyst. The phosphoric acid-containing catalyst consists in general ofa mixture of a relatively inert carrier, such as kieselguhr impregnatedwith the ortho or pyrophosphoric acid and is preferably precalcinedbefore using. When kusing the preferred catalyst, polymerizingtemperatures in the approximate range of 250 to 450 F. may be employedwith a superatmospheric pressure ranging, for example, fr om 500 to 1200pounds or more per square inch. Y

The products from the polymerization treatment in zone 21 are removedtherefrom by way of line 28 and introduced to stabilizing zone 29wherein the residual normally gaseous hydrocarbons are separated byfractionation from the normally liquid polymers. stabilizing zone 29, inthe case here illustrated, may be operated under a superatmosphericpressure of from 40 to pounds or more per square inch. Normally gaseoushydrocarbons separated in zone 23 are removed therefrom by way of line30 and recovered as a product of the process, and preferably the butanehydrocarbons contained therein are separated therefrom for blending toincrease the vapor pressure of the distillate recovered from theprocess.

Normally liquid polymers separated in zone 29 are removed therefrom byway of line 3| and a portion or all may be recovered as a product of theprocess by way ofline 32. Preferably,

however, and in accordance with the object of this invention. at least aportion of said normally liquid polymers are commingled with the normal-1y liquid hydrocarbons removed from zone I4 by way of line 33. Thenormally liquid hydrocarbons removed fromv zone I4 by vway of line 33may also be recovered in part or all as a product of the process by wayof line 34. However, they are preferably commingled with the normallyliquid polymers, as previously described, and the mixture introduced toline 35. In line 35 the normally liquid polymers and hydrocarbons arecommingled with light reflux condensate removed from zone I0 and themixture introduced to low temperature catalytic cracking system 36.

Low temperature catalytic cracking system 36 may comprise, for example,a heating coil to which the mixture is supplied for heating to thedesired conversion temperature. In addition, it may comprise a pluralityof reactor zones containing a cracking catalyst of essentially the samecomposition as that described in connection with the high temperaturecatalytic cracking treatment in system I6 to which the heated mixture issupplied. The low temperature catalytic cracking treatment in system 36may employ conversion temperatures ranging, for example, from 500 to 900F., pressures ranging, for example, from substantially atmospheric to200 pounds or more per square inch, and liquid hourly space velocitiesof from .5 to 2 volumes of hydrocarbon material per volume of catalyst.

The conversion products from system 38 are removed therefrom by way of.line 31 and introduced to fractionating zone 38, which is preferablymaintained at substantially the same or at a reduced pressure relativeto that employed in system 36. The conversion products introduced tozone 38 are subjected to fractionation therein to separate fractionatedvapors boiling in the range of gasoline from the higher boilinghydrocarbons and the latter condensed as reflux condensate in the`fractionating zone. Reflux condensate formed in zone 38 is removedtherefrom by way of line 39 and commingled in part or all with thereflux condensate from zone I3 in line 20 for conversion in system I6,or a portion or all .may be directed through line 40 and commingled withthe heavy reflux condensate from zone III in line I I for conversion insystem 2.

Fractionated vapors separated in zone 38 are removed therefrom by Way ofline 4I and subjected to cooling and condensation in condensing zone 42.Distillate, together with undissolved and uncondensed gases, aredirected from zone 42 through line 43 into receiving zone 44 where thedistillate and gases are collected and separated. Undissolved anduncondensed gases separated in zone 44 are removed therefrom by way ofline 45 and recovered as a product of the process. Distillate collectedand separated in zone 44 is removed therefrom by way of line 46 andrecovered as a product of the process.

-`An example of one speciiic operation of the process as above describedis approximately as follows:

A A. P. I. gravity Mid-Continent reduced crude oil was subjected toconversion in a heating coil at an outlet conversion temperaturel on theheating coil of 930 F. and an outlet pressure of 250 pounds per .squareinch, and the conversion products from the heating coil introduced to areaction chamber maintained at substantially the same pressure as thatemployed on the outlet of the heating coil.

In another step of the process, a' 54 A. P. I. gravity straight rungasoline from a Mid-Continent crude oil was subjected to pyrolyticreforming treatment in a heating coil employing an outlet temperature of1000" F. and an outlet pressure of approximately 750 pounds per squareinch.

'Ihe conversion products from. the reaction chamber were commingled withthe conversion products from the reforming treatmentand the mixtureintroduced to a vaporizing and separating chamber maintained at asuperatmospheric pressure of approximately 75 pounds per square inch. Inthe vaporizing and separating chamber non-vaporous liquid residue of 10A. P. I. gravity was separated from the vaporous conversion products andthe former recovered as a product of the process. The vaporousconversion products were introduced to a fractionator maintained atsubstantially-the same pressure as that maintained in the vaporizing andseparating chamber and subjected to fractionation therein to separatefractionated vapors boiling substantially in the range of gasoline fromthe higher boiling components and the latter condensedas light andheavyV reiiux condensate. The heavy reiiux condensate was subjected topyrolytic conversion in a third heating coil employing an outletconversion temperature of 945 F. and an outlet pressure of approximately250 pounds per 'square inch and the conversion products therefromcommingled with the conversion products from the rst mentioned heatingcoil prior to their introduction to the reaction chamber.

In another step of the process a 36 A. P. I. gravity gas-oil from aMid-Continent crude oil was vaporized and heated to a temperature of 950F. and the vapors subjected to contact with a silica-alumina-zirconiacatalyst at a pressure of approximately 60 pounds per square inch and aliquid hourly space velocity of 4. The conversion products from thistreatment were subjected to fractionation-at a superatmospheric pressuresubstantially the same as that employed in the catalytic conversionreaction to separate vapors boiling in the range of gasoline from thegether with the gaseous hydrocarbons formed in the process after coolingand condensation, were commingled and the mixture introduced to astabilizing Vzone maintained at aV superatmospheric pressure ofapproximatelyv 60 pounds per square inch whereby to separatesubstantially all of the normally gaseous hydrocarbons and hydrogen fromthe gasoline distillate.- The normally -gaseous hydrocarbons andhydrogen were introduced to a de-'ethanizing zone maintained at asuperatmospheric pressure of approximately 600 pounds per square inch toseparate the lighter gases, including those having two carbon atoms tothe molecule, from the heavier normally gaseous hydrocarbons and theformer recovered as a product of the process.l

The heavier normally gaseous hydrocarbons, y

comprising C3 and C4 hydrocarbons, were subjected to polymerization. inthe presence of a phosphoric acid-containing catalyst at a temperatureof 400 F. and a superatmospheric pressure of i000. pounds per square'inch. The products of thepolymerizationfreaction were fractioned at apressure of 60 pounds per square inch to separate residual normallygaseous hydrocarf bons from the normally liquid polymers and the formerrecovered as a product of the process.

The normally liquid polymers and the distillate were commingled withlight reux condensate. formed as previously described, and the mixtureheated to a temperature of '150 F. and subjected to contact with -asilica-aluminazirconia catalyst at a pressure of approximately 100pounds 'per square inch and a liquid hourly space velocity of 1. Theconversion products from this treatment were subjected to fractionationat a superatmosphe'ric pressure substantially the same as gasoline, 35%gas-oil, were approximately as follows:

60% 300A end point gasoline having an octane ratingof 71, a brominenumber of 9, and 27% of 10 A. P. I. gravity residue, the balance beingattributed principally to gas and loss.

I claim as my invention:

1. A conversion process which comprises subjecting hydrocarbonoil tothermal cracking, separating from the resultant products refluxcondensate heavier than gasoline, a gasoline distillate and a normallygaseous fraction containing polymerizable olens, subjecting saidfraction to polymerization, separating a polymer fraction boilingsubstantially within the range of gasoline from resultant olefinpolymers. and subject` ing said polymer fraction to the action of acracking catalyst at a temperature in the -approximate range of 500 to900 F. for a suicient time-and in admixture with a suiiicient quantityof said reflux condensate to substantially satu- -rate the polymers bythe transfer' of hydrogen thereto from the redux condensate.

2. A conversion process which comprises subjecting hydrocarbon Y oil tothermal cracking, separating from the resultant products reux condensateheavier than gasoline, a gasoline distillate and a normally gaseoustraction containing polymerizable oleins, subjecting said fraction topolymerization, separating a polymer'V fraction boiling substantiallywithin the range of gasoline from resultant olen polymers, andsubjecting Vsaid polymer fraction and at least a portion of saidgasoline distillate to the action of a. cracking catalyst atatemperature in the approximate range ot 500 to 900 F. for a suiiicienttime and in admixture with a suiiicient tions, theheavier fractionthereof returned to the thermal cracking and the lighter fractionthereof combined with the olefin polymers as the hydrogen donor in thecatalytic conversion step.

. tillate and a normally gaseous fraction containing 4. A conversionprocess which comprises thermally cracking hydrocarbon oil heavier thangasoline, thermally reforming a lighter oil containing gasolinefractionsof low anti-knock value, fractionating the products of thecracking and reforming steps in admixture to separate therefrom refluxcondensate heavier than gasoline, a gasoline distillate and a normallygaseous fraction containing polymerizable olens, subjecting saidfraction to polymerization, `combining resultant olefin polymers lwithat least a portion of said gasoline distillate. and subjecting theresultant mixture to the action of a cracking catalyst at a temperaturein the approximate range of 500 to 900 F. for a suiilcient time and inadmixture with a sufficient quantity of said reflux condensate tosubstantially saturate said mixture by the transfer of hydrogen theretofrom .the reux condensate.

5. The process as defined in claim 4 further characterized in that saidreflux condensate is separated into relatively light and heavyfractions, the heavier fraction thereof returned to the thermal crackingand the lighter fraction thereof combined withV the olefin polymers asthe hydrogen donor in the catalytic conversion step.

6. All process as defined in claim 4 whichgfurther includes catalyticcracking of a second oil heavier than gasoline and the combining ofresultant oiefinic gasoline with the materials subjected to the actionof said cracking catalyst.

7. A conversion process which comprises Vsubjecting hydrocarbon oil tothermal cracking, separating from the resultant products refluxcondensate heavier than gasoline, a gasoline dispolymerizableoleflns,subjecting said fraction to polymerization, separating a polymerfraction boiling substantially within the range of gasoline fromresultant olefin polymers, and subjecting at least a portion of saidpolymer fraction to the action of a cracking catalyst at a temperaturein the approximate range of 500 to 900 F.

for a suicient time and in admixture with a' sufcient quantity of saidreux condensate to substantially saturate the polymers by the transferof hydrogen thereto from the reflux condensate.

8. A conversion process which comprises subjecting hydrocarbon oil tothermal cracking, separating from the resultant products refluxoondensate heavier than gasoline, a gasoline distillate and a normallygaseous fraction containing polymerizable olens, subjecting saidfraction to polymerization, simultaneously subjecting anotherhydrocarbon oil, heavier than gasoline, to

i catalytic cracking, combining resultant olefin polymers with resultantolefinic gasoline formed in the catalytic cracking step, and subjectingthe mixture to the action of, a cracking catalyst at a temperature inthe approximate range of 500 to 900 F. for a sufficient time and inadmixture with a suillcient quantity of said reilux condensate tosubstantially saturate the gasoline and 'polymers by the transfer ofhydrogen thereto from the reux condensate. EDWIN' H. MCGREW.

